Hygroscope



R. F. REED Dec. 11; 1934.

HYGROSGOPE Filed June 2, 1931 2 Sheets-Sheet 1 'WXM W76, ATTORNEYS R.F., REED HYGROSCOPE Filed June 2, 1931 Sheets-Sheet 2 Jim WE Iii/7mINVENTOR ATTORNEYS Patented Dec. 11, 1934 UNITED STATES HYGBOSCOPERobert F. Reed, Norwood, Ohio, assignor to The lithographic TechnicalFoundation, Inc., New York, N, Y., a corporation of Delaware ApplicationJune 2, 1931, Serial No. 541,040

5- Claims. (01. 13-24) This invention relates to an article adapted toindicate the degree of variance between the moisture content of airentrained in a pile of paper and the moisture content of the atmospheresurrounding the pile of paper.

Attempts have been made in the past to measure the moisture content ofpaper in the pile by means of a hygrometer designed to read. in terms orpercentage relative humidity or percentage moisture. Hygrometersactuated by hygroscopic elements possess the disadvantage in that thehygroscopic element tends to stretch as a result of prolonged usage withthe result that a cumulative error in the readingsisdeveloped. Theconcept of, this invention is to provide a paper hygroscope adapted toindicate whether or not pilesof paper are in a condition of hygrometricequilibrium with the atmosphere of the work roomin which they arehandled.

The instrument, therefore, is intended and adapted not to providereadings in terms or moisture content, but to indicate the humidity ofthe pile of paper inrelation to the existing humidity of the atmosphereof the room. By .this method one may obtain accurate information fromday to day whether or not the piles 01' paper to be used are in propercondition for working without having the calculations subject to errorsresulting from change of condition or elasticity of the delicatehygroscopic element.

This instrument should be of particular value to lithographers andprinters who operate sheetied presses. It is not a hygrometer and givesno reading in terms of moisture content or relative humidity. a

The object of the invention is to provide an accurate instrument of thenature heretofore described, properly constructed and proportioned toindicate deviations in moisture content and provided with indicatingmechanism of a type adapted to be most easily readable for informing theuser whether or not there is hygrometric equilibrium between theatmosphere of the work room and the paper to be handled. Other objectsand further advantages will be more fully apparent from a description ofthe accompanying drawings, in which:

Figure '1 is a side elevation of the hygroscope. Figure 2 is a sectionalview taken on line 2-2, Figure 1, illustrating the construction of theblade and arrangement of the hygroscopic element and its connection tothe indicating hand operating mechanism at the handle.

Figure 3 is a perspectiveview generally lllustrating the moisturesensitive or hygroscopic actuating element.

' Figure 4 is a sectional view taken on line 4-4, Figure 1, detailingthe arrangement of the tape in the blade connecting the actuatingelement and the transmission at the indicating hand.

Figure ,5 is a sectional view taken on line 5-5, Figure 1, detailing thearrangement of the actuating or'moisture sensitive element within theblade.

Figure 6 is a fragmentary iront view of the portion of the'hygroscope atthe dial casing, the dial being removed for illustrating the indicatinghand motion increasing means.

Figure 7 is a sectional view taken on line 77, Figure 6; furtherillustrating the motion transmitting and increasing mechanism betweenthe moisture sensitive element and the indicating hand as wellasthe'movable dial.

Figure 8 is a fragmentary view taken similar to. Figure 6 but showingthe dial casing entirely removed for illustrating the coil springtensioning the hygroscopic element and balancing or stabilizing .theindicating hand.

Figure 9 is a sectional view taken on line 9--9, Figure 6, furtherdetailing the motion transmitting and increasing mechanism.

, Figure 10 be general fragmentary view illustrating a stack of paperwith the hygroscope placed in position between the sheets thereof fordetermining the difference in moisture content of the paper and thehumidity of the room.

The hygroscope consists of a sword-like blade which can be insertedbetween the sheets in a pile of paper 16 (see Figure 10). A movable-hilt 17 is provided to regulate the'distance to which the blade isinserted and to cover the opening in the pile. The blade carries apartially enclosed hygroscopic element 18 which is connected by means ofmetal tape 19 to a pulley 20 which actuates an indicating hand 21through a motion increasing mechanism. A movable dial 22 is provided forthe purpose of facilitating accurate observation or the movement of theindicating hand. The pulley, motion increasing mechanism, indicatinghand, and dial are contained in the external handle 23 of theinstrument.

The hygroscopic element preferably comprises gold beaters skin on whicha pull such as 100 grams, is exerted.

Multiplying mechanism is used to translate stretch and shrinkage of thehygroscopic element, as transmitted by the connecting metal spacerannulus 42 by an upper annulus 43, the

tape, into rotation of the indicating hand in such manner that a 5%change in relative humidity of the atmosphere surrounding thehygroscopic element, in the range between 45 and 55% relative humidity,will cause the hand to rotate through an angle of 30.

The blade 15 is of hollow structure for containing the moisturesensitive element or actuating element 18. It has a sharp point forready insertion of the blade between sheets of a pile of paper and itsgeneral cross sectional contour is relatively fiat with rounded sideedges.

The blade is preferably elliptical or substan tially so in cross sectionwhereby the weight of the paper can be more uniformly distributed overits surface and perfect contact assured with no possibility of airpassage between the blade and paper. Moreover, the danger of tearing andabrasion of the surface of the paper is minimized.

The hygroscopic element or moisture sensitive element is composed'of astrip of gold beaters skin having its ends bound by fabric strips 24adhesively or otherwise attached in overlapped position. Eyelets 25 areprovided at the respective ends of the element, being formed of wirehaving central eyelet portions and side extensions contained within thebight of the overlapped fabric, the eyelet protruding through anaperture in the fabric centrally of the ends of the element. The elementthus formed is mounted within a longitudinal channel 26 within the bladeand is extended as nearly ad- J'acent the tip of the blade as possible.At the sides of the channel or element 18 the blade is open to theatmosphere or the paper through a series of openings 27 disposed alongthe blade sides. At one side the apertured wall is removable, being inthe form of a ported plate 28.

The outer end of the hygroscopic element 18 is.fixed to be blade bymeans of 'a screw 29 extending through the eyelet into the blade. At theinner end of the hygroscopic element 18 the end of a steel tape or wire19 is attached thereto, this tape or wire extending through a narrowslot or channel 30 in that side of the blade adjacent the removableplate and having its end attached to the grooved pulley 20 journalledwithin a chamber 31 formed in the handle portion of the instrument.

This pulley 20 is fixed to a shaft 32 journalled in the handle, whichshaft also has a large gear 33 fixed thereto and meshing with a smallgear 34 fixed to a shaft 35 which is concentric with the dial casing.This centrally disposed shaft carries the indicating hand 21. Thecircular dial casing 36 is attached upon the handle by means of aplurality of screws 37 extending through the bottom of the dishlike dialcasing 36 and into a plate 38 seated in a rectangular recess 39 on theopposite side of the handle element, spacers 40 being provided betweenthe bottom of the casing and the disk within the chamber 31 previouslymentioned, the, screws therefor clamping the casing 36 and plate 38 inposition.

- The shafts mentioned have their inner ends journalled in the plate 38and their upper ends journalled in disks 41: fixed intermediately of thedepth of the casing. These disks within the casing are secured in spacedrelation to the bottom of the casing by means of a spacer annulus 42fitting within the circular casing below the same and are held inposition against the movable dial 22 or glass disk being mounted uponthe top of this upper annulus. The annuli 42, 43, the metal disks 41 andthe dial or glass disk 22 are maintained in position by means of acollar 44 screwed upon the casing and having a flange 45 overhanging thedial or glass disk 22.

The indicating hand 21 is fixed to the central shaft 35 between themetal disk and the glass disk so as to be visible through the glass. Thetransmission and hygroscopic elements are placed under a tensioning andstabilizing force by means of a clock spring 46 having its inner endfixed to the central shaft 35 and its outer end attached -to one of thecasing securing spacer elements 40. Undueoutward spring of the clockspring is prevented when the same is relaxed by'engagement thereof withanother of the casing anchoringspacer elements 40. The spring iseifective for placing the hygroscopic element 18 under a normal pull of100 grams, assuring a constant tautnessthereof.

It will be seen that the position of the indicating hand is determinedby the contraction and expansion of the hygroscopic or moisturesensitive element in the blade since the most minor or almostunnoticeable change in the length of this element will be effective foractu. ating the transmission and the movement will be increased throughthe large gear meshing with the small gear for increased movement of the-indicating hand proportionate to the expansion and contraction movementof the sinsitive element. Therefore, its position will be a variableone, depending on the atmospheric conditions surrounding the instrument;

To determine the change .or fluctuation of the hand, due to expansion orcontraction of the hygroscopic element, the glass disk or dial 22 ismanually rotatable within the casing, operation being accomplishedthrough a knob 47 secured to the glass adjacent 'the periphery thereofby means of a screw 48 extended into the knob from the inside of theglass. The dial 22 has felt washers 49 above and below-for securing itagainst normal displacement but permitting rotative manipulation.

This glass dial or disk 22 has a plurality of markings on its peripheralmargin on the under side thereof. These consist of three indicatingpoints or arrows, the intermediate of which, namely 50, is adapted to beregistered with the indicating hand and the outer of which, namely 51,are each spaced 15 from the intermediate and are limit indicatingpoints. Beyond these points the periphery is suitably marked as at 52 toidentify further degrees of indicating hand variation from theintermediate marking.

The adjustable hilt 17 is secured in position on the blade for limitingblade insertion as determined by the width of the paper pile by means ofthe set screw 53. It is preferable that the blade extend to the centerof the pile for accurategeading.

In operation, the operator'first satisfies him- .self thatthe hygroscopeis atv equilibrium with the atmosphere of the room. He does this bysetting the central or intermediate indicating point on the movable dialopposite the indicating hand and swinging the instrument in the air forone minute. If the central or intermediate indicating point is not stillopposite the indicating hand, he resets it to this point and repeats the7 operation until the registration of the indicating hand with theintermediate point is approxthan that bounded by the intermediateindicat-,

masses \1 imately maintained during one minute. He nextinsertsthebladeinthepileofsheetstoflie desired distance and noteswhether or not the indicating hand rotates through an are greateringpointoithedialandoneoitheadjacent limit indicating points within aperiod of two minutes.

It the, indicating hand does not pass either of the limit indicatingpoints, the papermay be safeLv printed without further conditioning,under the existing atmospheric conditions. If; however, the indicatinghand passes either of the limit indicating points, the paper should beconditioned to the pressroom atmosphere before Printing. Havingdescribed the invention, I desire to be limited only by the followingclaims: v 1. 4 hygroscope, comprising, a hollow apertured blade, ahygroscopic element disposed in said blade, means for maintaining saidelement in taut condition, an indicating device, a trans-1 missionmechanism for actuating said indicating device, a connecting element ofmetal tape between said hygroscopic element and said transmissionmechanism, wherebythe transmission mechanism is capable oi magnifyingthe expansion and contraction movements of the hygroscopic element forcausing the indicating device to show plus or minus deviations from aknown or determinable moisture content.

2. A hygroscope adapted to be inserted between sheets ot a pile of papercomprising, a

hollow apertured blade, an adjustable hilt mounted on said blade, -ahygroscopic element mounted in said blade, said blade having curvedsurfaces for maximum contact with the paper, and an indicating means onthe handle of the blade connected to said hygroscopic element for 40showing the variation between conditions of humidity in the room and inthe paper pile. 3. A hygroscope, comprising, a hollow apertured bladeadapted to be inserted between the sheets of a pile of paper, a handlefor said' blade,

5 a hygroscopic element longitudinallydisposed within the blade towardthe outer end thereof, said hygroscopic element composed of a moisturesensitive sheet of material readily expansible and contractible, amotion increasing trans- 50 mission connected to said moisture sensitiveele- V a ment for increasing and converting the move ment derivedtherefrom into rotative movement,

an indicating hand connected to and actuated by said transmission,tensioning means in the transmission for maintainingthe hygroscopicelement in taut condition and the indicating hand in stabilized normalposition, and an adjustable marked dial movable relative to theindicating hand for initially setting a mark relative to the indicatinghandwhen the hygroscope is exposed to atmospheric conditions in'the roomwhereby variations thereim when the hist.scopeisinpositionoiusemaybeindicatedby movement of the said mark;

4. A hygroscope, comprising, a hollow aperindicating hand relative totured blade adapted to be inserted between the sheets of a pile ofpaper,'a handle ior said blade, a hygroscopic element disposed withinthe blade toward the point thereof, said hygroscopic element composed ofamoisture sensitive sheet 01' material readily expansible andcontractible, a

motion increasing transmission connected to said eating device, aconnection between said motion increasing transmission and saidhygroscopic element, and means for maintaining said hygroscopic elementin taut condition, whereby the transmission mechanism is capable ofmagnifying the expansion and contraction movements oi the hygroscopicelement for causing the indicating device to show plus or minusdeviation from an initial setting. A

ROBERT F. REED.

creasing transmission for actuating said indi-

